First start GDB in the root directory of your Linux kernel, using the
vmlinux kernel image as file to debug:

bash$ cd <linux-root>
bash$ ${CROSS_COMPILE}gdb vmlinux
GNU gdb 5.1.1
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "--host=i386-redhat-linux --target=ppc-linux".
(gdb)

The option -m prints out the addresses of the
various code and data segments (
.text,
.data,
.sdata,
.bss,
.sbss
) after relocation. GDB needs these
addresses to know where all the symbols are located. We now
interrupt GDB to load the symbol table of the module as follows: